JP3540708B2 - Dual fuel engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dual fuel engine.
[0002]
[Prior art]
Conventionally, the liquid fuel nozzle and the gas fuel nozzle face the same intake passage, and the fuel switch switches the supply of the liquid fuel and the gas fuel to each other to perform the liquid fuel operation and the gas fuel operation. There is a type in which a choke valve is provided on the intake upstream side of each of the nozzles. In this engine, the choke valve is manually opened and closed.
[0003]
[Problems to be solved by the invention]
The above prior art has the following problems.
<< 1 >> The gas fuel start may fail.
When starting gas fuel, there is a case where the choke valve is closed by mistake. In this case, the supply amount of the gas fuel becomes excessive, and the gas fuel start may fail. Further, even if the choke valve is opened and closed by an existing automatic choke mechanism, the gas fuel start may fail in cold weather because the choke valve is closed.
[0004]
<< 2 >> The liquid fuel cold start may fail.
When performing the liquid fuel cold start, there is a case where the choke valve is erroneously opened while being performed. In this case, the supply amount of the liquid fuel is insufficient, and the liquid fuel cold start may fail. In addition, the choke valve is closed at first, but the choke valve may be accidentally fully opened immediately after the start of the engine and before the engine temperature is sufficiently increased. In this case, the supply amount of the liquid fuel decreases at a stretch, and the liquid fuel cold start may fail.
[0005]
<< 3 >> The liquid fuel temperature start may fail.
When performing the liquid fuel temperature start, there is a case where the start is performed while the choke valve is closed by mistake. In this case, the supply amount of the liquid fuel becomes excessive, and the liquid fuel temperature start may fail.
[0006]
An object of the present invention is to provide a dual fuel engine that can solve the above problems.
[0007]
[Means for Solving the Problems]
(Invention of claim 1)
The configuration of the invention of claim 1 is as follows.
As shown in FIG. 1, the liquid fuel nozzle (1) and the gas fuel nozzle (2) face the same intake passage (3), and the supply of the liquid fuel and the gas fuel is performed by the fuel switch (4). In a dual fuel engine, the liquid fuel operation and the gas fuel operation are performed by switching each other, and a choke valve (5) is provided upstream of each of the nozzles (1) and (2) on the intake side.
As shown in FIG. 1, when the choke valve opening / closing means (6) is provided and the fuel changeover switch (4) is at the gas fuel position, as shown in FIG. The choke valve opening / closing means (6) opens the choke valve (5) fully before the start of the operation of the starter (11) or until a predetermined time elapses from the start time (7) of the starter (11). A dual fuel engine characterized in that the choke valve opening / closing means (6) keeps the choke valve (5) fully open during a period (37) from 8) to an engine stop operation point (36). .
[0008]
(Claim 2)
The structure of the invention according to claim 2 is as follows.
The dual fuel engine according to claim 1,
When the fuel changeover switch (4) is in the liquid fuel position and the engine temperature is in the predetermined cold start temperature range, as shown in FIG. 4, the operation start time (7) of the starter (11) is started. During a period (39) from the time point till when the engine temperature exceeds the predetermined cold start temperature range (38), the choke valve opening / closing means (6) puts the choke valve (5) in the fully closed state, and the engine temperature starts cold start. During a period (41) from a point (38) exceeding the temperature range to a point (40) at which a predetermined choke end temperature is reached, as the engine temperature rises, the choke valve opening / closing means (6) moves the choke valve (5). Gradually approaches the fully open state, and during the period (42) from the time (40) when the engine temperature reaches the choke end temperature to the time (36) of the engine stop operation, the choke valve opening / closing means (6) operates the choke valve (5). ) Is kept fully open Dual fuel engine, characterized in that.
[0009]
(Claim 3)
The structure of the invention according to claim 3 is as follows.
The dual fuel engine according to claim 2,
When the fuel changeover switch (4) is in the liquid fuel position and the engine temperature exceeds the choke end temperature, as shown in FIG. 5, the operation start time (7) of the starter (11) is started. Before the predetermined time (43) elapses, the choke valve opening / closing means (6) fully opens the choke valve (5), and the time from when the choke valve (5) is fully opened (8) to when the engine is stopped (36). A dual fuel engine, wherein the choke valve opening / closing means (5) keeps the choke valve (5) fully open during the period (37).
[0010]
Function and effect of the present invention
(Invention of claim 1)
The invention of claim 1 has the following operation and effect.
<< 1 >> Failure of starting gas fuel can be prevented.
As shown in FIG. 3, at the time of starting the gas fuel, the choke valve () is operated before the start time (7) of the operation of the starter (11) or until a predetermined time elapses from the start time (7) of the operation of the starter (11). Since 5) can be fully opened, an appropriate amount of gas fuel can be supplied, and failure in starting gas fuel can be prevented.
[0011]
(Invention of claim 2)
The invention of claim 2 has the following effect in addition to the effect of the invention of claim 1.
<< 2 >> Failure of cold start of liquid fuel can be prevented.
As shown in FIG. 4, at the time of liquid fuel cold start, the choke valve (5) is fully closed from the start of operation (7) of the starter (11), and the choke valve (5) is turned on as the engine temperature rises. Since the state is gradually approached to the fully opened state, an appropriate amount of liquid fuel is supplied, and failure of the liquid fuel cold start can be prevented.
[0012]
(Invention of claim 3)
According to the third aspect of the invention, in addition to the effects of the second aspect of the invention, the following operation and effect can be achieved.
As shown in FIG. 5, at the time of starting the liquid fuel temperature, the choke valve (5) can be fully opened until a predetermined time (43) elapses from the operation start time (7) of the starter (11). An appropriate amount of liquid fuel is supplied, and failure of liquid fuel temperature start can be prevented.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
1 to 5 are diagrams illustrating a dual fuel engine according to an embodiment of the present invention. This engine performs liquid fuel operation and gas fuel operation by switching the supply of liquid fuel and gas fuel to each other, and can prevent failure of engine start. This engine comprises a fuel mixer (10), a fuel selector switch (4), a cell starter (11), a spark plug (9), a key switch (13), a battery (12), and a choke valve opening / closing means (6). ing.
[0014]
The configuration of the fuel mixer (10) is as follows.
As shown in FIG. 2, the fuel mixer (10) includes a mixing body (14) and a liquid fuel cup (15). A gas fuel inlet pipe (16), a gas fuel cutoff valve (17), a gas fuel cutoff valve actuator (24), and a gas fuel nozzle (2) are attached to an upper portion of the mixing body (14). 3) and a gas fuel relay passage (18) are formed. As shown in FIG. 1, the intake passage (3) includes a choke valve (5) on the upstream side of the intake and a throttle valve (19) on the downstream side of the intake. The throttle valve (19) is operatively connected to a speed control lever (23) via a connecting rod (20), a governor lever (21), and a governor spring (22), and a governor spring force (22a) applied to the governor lever (21). The opening degree of the throttle valve (19) is adjusted by the unbalance force between the governor force (21a) and the governor force (21a). The gas fuel inlet pipe (16) is connected to a gas fuel cylinder (not shown) via a regulator (not shown). The gas fuel cylinder is filled with LP gas (liquefied petroleum gas).
[0015]
As shown in FIG. 2, the gas fuel shutoff valve (17) includes a valve element (17a) and a valve seat (17b), and the valve element (17a) is connected to an output rod of a gas fuel shutoff valve actuator (24). The valve body (17b) is attached to the inlet of the gas fuel relay passage (18). The gas fuel nozzle (2) is attached to the lower end of the gas fuel relay passage (18), and the outlet at the lower end faces the intake passage (3). The inlet at the upper end of the gas fuel nozzle (2) communicates with the gas fuel inlet pipe (16) through the gas fuel relay passage (18) and the valve seat (17b) of the gas fuel cutoff valve (17), and the communication therewith. Is shut off by closing the gas fuel shutoff valve (17).
[0016]
A liquid fuel nozzle (1) is attached to a lower portion of the mixing body (14). The liquid fuel nozzle (1) has an upper end outlet facing the intake passage (3). The liquid fuel cup (15) is attached to the lower part of the mixing body (14) and contains a float valve (26) in the liquid fuel chamber (25). The liquid fuel chamber (25) is connected to a liquid fuel tank (not shown) via a fuel supply pump (not shown). The liquid fuel tank is filled with gasoline. A liquid fuel cutoff valve (27) and a liquid fuel cutoff valve actuator (28) are attached to the liquid fuel cup (15). The liquid fuel cutoff valve (27) includes a valve body (27a) and a valve seat (27b). The valve body (27a) is attached to an output rod of an actuator (28) for a liquid fuel cutoff valve. ) Is attached to the inner bottom of the liquid fuel cup (15). The inlet at the lower end of the liquid fuel nozzle (1) communicates with the liquid fuel chamber (25) via a valve seat (27b), and the communication is shut off by closing the liquid fuel cutoff valve (27). Each outlet of the liquid fuel nozzle (1) and the gas fuel nozzle (2) faces the same intake passage (3), and a choke valve (5) is provided upstream of each nozzle (1) (2) on the intake side. I have.
[0017]
The configuration of the fuel changeover switch (4) and the like is as follows.
As shown in FIG. 1, the fuel changeover switch (4) includes a gas fuel terminal (4a) and a liquid fuel terminal (4b), and the gas fuel terminal (4a) is connected to a gas fuel shut-off valve actuator (24). ), The gas fuel shut-off valve actuator (24) closes the gas fuel shut-off valve (17) when not energized, and opens the gas fuel shut-off valve (17) when energized. I do. The liquid fuel terminal (4b) is connected to the liquid fuel cutoff valve actuator (28), and the liquid fuel cutoff valve actuator (28) closes the liquid fuel cutoff valve (27) when not energized, During energization, the liquid fuel cutoff valve (27) is opened. The cell starter (11) includes an output rod (11a) and a pinion gear (11b). The pinion gear (11b) is attached to the output rod (11a), and a ring gear (11) is attached to the crankshaft (29). We are facing 29a). When energized, the cell starter (11) engages the pinion gear (11b) with the ring gear (29a) while rotating the output rod (11a), and when the rotation speed of the crankshaft (29) exceeds a certain value, the The two-on gear (11b) is disengaged from the ring gear (29a), and the operation is stopped. The spark plug (9) is connected to the igniter (9a) and discharges a spark to a combustion chamber (not shown) at a predetermined timing.
[0018]
The key switch (13) has an OFF position (OFF position), an ACC position (accessory position), an ON position (ON position), and a START position (start position). The key switch (13) is connected to the battery (12). When the key switch (13) is placed in the ACC position, the battery (12) is connected to the fuel switch (4). 4) and the igniter (9a), and when put into the START position, the battery (12) is connected to the fuel switch (4), the igniter (9a) and the cell starter (11).
[0019]
The structure of the choke valve opening / closing means (6) is as follows.
As shown in FIG. 1, the choke valve opening / closing means (6) includes an urging spring (30), a stroke adjusting spring (31), a diaphragm actuator (32), a boost valve (33), and an electric actuator (34). Have. The biasing spring (30) biases the choke valve (5) to the fully closed side. The diaphragm actuator (32) is connected to the downstream side of the throttle valve (19) via a boost valve (33). The boost valve (33) has its temperature sensing part (33a) inserted into the engine cooling water jacket (35), and when the engine temperature is in a predetermined cold start temperature region (for example, in a region of −10 ° C. or less, Until the engine temperature reaches a predetermined choke end temperature (for example, 0 ° C.), the engine fully approaches the fully open state until the engine temperature reaches the predetermined choke end temperature (for example, 0 ° C.). The electric actuator (34) is connected to the gas fuel terminal (4a) of the fuel selector switch (4), and the choke valve (5) is connected to the diaphragm via a stroke adjusting spring (31). The actuator (32) and the electric actuator (34) are operatively connected.
[0020]
When the boost valve (33) is in a closed state, the boost pressure (negative pressure) downstream of the intake passage (3) does not act on the diaphragm actuator (32). When the boost valve (33) is in the open state, the boost pressure applied to the diaphragm actuator (32) gradually increases as the opening degree increases, and the diaphragm actuator (32) opens the choke valve (5). Gradually increase the degree. The electric actuator (4) makes the choke valve (5) fully open when energized, and does not act on the choke valve (5) when not energized.
[0021]
The functions of the choke valve opening / closing means (6) and the like are as follows.
As shown in FIG. 3, when the fuel changeover switch (4) is in the gas fuel position and the key switch (13) is turned to the ACC position, the liquid fuel cutoff valve (27) maintains the closed state. The fuel cutoff valve (17) is opened, and the electric actuator (34) starts opening the choke valve (5) against the urging force of the urging spring (30). When the key switch (13) is moved to the START position beyond the ON position, the cell starter (11) starts operating, sparks jump from the spark plug (9), and the engine starts. When the key switch (13) is returned to the ON position or the engine speed exceeds a predetermined value, the pinion gear (11b) of the cell starter (11) is disengaged from the ring gear (29a), and the operation of the cell starter (11) is started. Stops. Even if the key switch (13) is returned to the ON position, the spark continues to flow from the spark plug (9) and the engine is continuously operated. When the key switch (13) is returned from the ON position to the ACC position, the spark stops flowing from the spark plug (9) and the engine stops. Further, when the key switch (13) is returned to the OFF position, the gas fuel cutoff valve (17) is closed, the power to the electric actuator (34) is released, and the choke valve (5) is turned on by the biasing spring ( Fully closed with the biasing force of 30).
[0022]
When the engine is started, the electric actuator (34) is energized from the time the key switch (13) enters the ACC position, and the choke valve (34) starts to open. When the start time is maintained () 3 seconds), the electric actuator (34) fully opens the choke valve (5) before the operation start time (7) of the starter (11). In the case where the maintenance period of the ACC position is short (for example, 1 second or less), the electric actuator (5) is required until a predetermined time (for example, 1 to 3 seconds) elapses from the operation start time (7) of the starter (11). Opens the choke valve (5) fully. If the period from the start of operation (7) of the starter (11) to the full opening of the choke valve (5) is long, gas fuel is excessively sucked into the intake passage before the opening of the choke valve (5), and starting may fail. The opening speed of the choke valve (5) by the electric actuator (34) is increased, and the choke valve is started within 3 seconds, preferably within 2 seconds, more preferably within 1 second from the start of operation (7) of the starter (11). (5) should be fully open. As described above, the choke valve opening / closing means (6) switches the choke valve (5) before the operation start time (7) of the starter (11) or until a predetermined time has elapsed from the operation start time (7) of the starter (11). ) Is fully opened, and the electric actuator (34) maintains the choke valve (5) in a fully open state during a period (37) from the fully open time (8) of the choke valve (5) to the engine stop operation time (36). .
[0023]
During the period of energizing the electric actuator (34), the electric actuator (34) overcomes the diaphragm actuator (32) and acts on the choke valve (5), so during this period, the boost valve (3) is opened. Regardless of the degree, the choke valve (5) is fully opened by the electric actuator (34) and is maintained in the fully open state. When the fuel selector switch (4) is switched to the liquid fuel position during the gas fuel operation, the gas fuel cutoff valve (17) is closed, the liquid fuel cutoff valve (27) is opened, and the liquid fuel operation is started. Switch. During operation of the liquid fuel, the electric actuator (34) is not energized, but the choke valve (5) is maintained in the fully open state by the diaphragm actuator (32).
[0024]
As shown in FIG. 4, when the fuel changeover switch (4) is in the liquid fuel position and the engine temperature is in the cold start temperature range, when the key switch (13) is turned to the ACC position, the liquid fuel is shut off. The valve (27) is opened, and the gas fuel cutoff valve (17) is maintained in the open state. The electric actuator (34) is not energized, the boost valve (33) is also closed, and the choke valve (5) is fully closed by the urging force of the urging spring (33). The operation of the cell starter (11), the operation of the spark plug (9), and the like from the time when the key switch (13) is moved from the ON position to the START position until the key switch (13) is returned to the ACC position are the same as those in the case of the gas start. . Further, when the key switch (13) is returned to the OFF position, the liquid fuel cutoff valve (27) is closed. The electric actuator (34) is not energized to the end.
[0025]
During a period (39) from a time point (7) at which the starter (11) starts operating to a time point (38) at which the engine temperature exceeds a predetermined cold start temperature range, the boost valve (33) is maintained in a fully closed state. Since the electric actuator (34) is not energized, the choke valve (5) is fully closed by the urging force of the urging spring (30) and the engine temperature exceeds the cold start temperature range (38). During the period (41) from the time when the predetermined choke end temperature is reached to the time (40), as the engine temperature rises, the boost valve (33) gradually approaches the fully open state, and the boost acting on the diaphragm actuator (32) is increased. The pressure gradually increases, and the choke valve (5) gradually approaches a fully opened state. During a period (42) from the time point (40) when the engine temperature reaches the choke end temperature to the time point (36) of the engine stop operation, the boost valve (33) is maintained in the fully open state, and the choke is performed by the diaphragm actuator (32). Maintain valve (5) fully open. When the fuel switch 4 is switched to the gas fuel position during the liquid fuel operation, the liquid fuel cutoff valve 27 is closed, the gas fuel cutoff valve 17 is opened, and the gas fuel operation is started. Switch. During the gas fuel operation, the electric actuator (34) is energized, and the choke valve (5) is maintained in the fully open state by the electric actuator (34).
[0026]
As shown in FIG. 5, when the fuel changeover switch (4) is in the liquid fuel position and the engine temperature exceeds the choke end temperature, the operation start time (7) of the cell starter (11) is started. Since the boost valve (33) has already been fully opened, the boost pressure increases with an increase in the engine rotation speed of the cell starter (11), and a predetermined time (43) from the operation start time (7) of the cell starter (11). ), The diaphragm actuator (32) fully opens the choke valve (5), and a period from the time (8) when the choke valve (5) of the choke valve (5) is fully opened to the time (36) when the engine is stopped. During (37), the choke valve (5) is maintained in the fully open state by the diaphragm actuator (32). If the time from the start of the operation of the cell starter (11) (7) to the closing of the choke valve (5) is long, excessive liquid fuel may be sucked into the intake passage and the start may fail. The valve opening speed of the choke valve (5) by (32) is increased, and the choke valve (5) is started within 7 seconds, preferably within 5 seconds, more preferably within 3 seconds from the start of operation (7) of the cell starter (11). Make sure that 5) can be fully opened.
[Brief description of the drawings]
FIG. 1 is a schematic plan view of a main part of an engine according to an embodiment of the present invention.
FIG. 2 is a vertical sectional front view of a fuel mixer used in the engine of FIG. 1;
FIG. 3 is a time chart at the time of cold start of gas fuel of the engine of FIG. 1;
FIG. 4 is a time chart at the time of liquid fuel cold start of the engine of FIG. 1;
FIG. 5 is a time chart at the time of starting the liquid fuel temperature of the engine of FIG. 1;
[Explanation of symbols]
(1) liquid fuel nozzle, (2) gas fuel nozzle, (3) intake passage, (4) fuel selector switch, (5) choke valve, (6) choke valve opening / closing means, (7) ... Start time of starter operation, (8) ... Full open time of the choke valve, (11) ... Starter, (36) ... Engine stop operation time, (37) ... Period, (38) ... Time beyond the cold start temperature range, (39) ... period, (40) ... time when the choke end temperature is reached, (41) ... period, (42) ... period, (43) ... predetermined time.

Claims (3)

The liquid fuel nozzle (1) and the gas fuel nozzle (2) face the same intake passage (3), and the supply of the liquid fuel and the gas fuel is switched by the fuel selector switch (4). In a dual fuel engine, which performs an operation and a gas fuel operation, and is provided with a choke valve (5) on the intake upstream side of the nozzles (1) and (2),
When the choke valve opening / closing means (6) is provided and the fuel changeover switch (4) is at the gas fuel position, the operation start time (7) of the starter (11) or the operation start time of the starter (11) ( Until a predetermined time elapses from 7), the choke valve opening / closing means (6) opens the choke valve (5) fully, and the period from the time (8) of the choke valve (5) fully open to the time (36) of the engine stop operation ( 37) A dual fuel engine wherein the choke valve opening / closing means (6) keeps the choke valve (5) fully open during the operation. The dual fuel engine according to claim 1,
When the fuel changeover switch (4) is in the liquid fuel position and the engine temperature is in the predetermined cold start temperature range, the engine temperature is lowered to the predetermined cold start from the start of operation (7) of the starter (11). During the period (39) up to the point (38) exceeding the starting temperature range, the choke valve opening / closing means (6) closes the choke valve (5) completely, and the engine temperature exceeds the cold starting temperature range (38). ) To the time (40) when the predetermined choke end temperature is reached, as the engine temperature rises, the choke valve opening / closing means (6) gradually brings the choke valve (5) closer to the fully open state as the engine temperature rises, The choke valve opening / closing means (6) maintains the choke valve (5) in a fully open state during a period (42) from the time (40) when the engine temperature reaches the choke end temperature to the engine stop operation time (36). Characterized by the fact that Yuaru fuel engine. The dual fuel engine according to claim 2,
When the fuel changeover switch (4) is in the liquid fuel position and the engine temperature exceeds the choke end temperature, a predetermined time (43) is started from the operation start time (7) of the starter (11). Until the passage, the choke valve opening / closing means (6) fully opens the choke valve (5), and during the period (37) from the time (8) when the choke valve (5) is fully opened to the time (36) for stopping the engine, A dual fuel engine, wherein the choke valve opening / closing means (5) maintains the choke valve (5) in a fully open state.

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